Device for joining, by friction stir welding, at least two workpieces

A device for joining, by friction stir welding, at least two workpieces which are disposed adjacent one another in the area in which they are to be joined, said device comprising:

• a support structure including a head portion, a rotatable shaft supported on said head portion and having one end connected to drive means for rotating said shaft, said shaft having at its other end a pin-like projection, said support structure further including a support member for supporting said at least two workpieces below said pin-like projection, guide means for moving said rotating pin-like projection toward said at least two workpieces disposed on said support member and into contact therewith for plasticizing said workpieces in the contact area to form thereby a spot weld by friction stir welding, said guide means including pivot arms supporting said head portion so as to permit movement of said head portion with said pin-like projection about an axis which is essentially parallel to the pin-like projection for providing a lateral extension of said welding spot.